How do you people easily switch between compiler versions?
afaik there are several options.
In one setup i let every fpc have it's own configuration file set the cfgdir to a common root and include a common fpc.cfg that is used by all FPC versions (correct directory tree is important there). You could also use environment variable PPC_CONFIG_PATH for that of course but, i like to stay flexible just in case it is needed.
Then, inside common fpc.cfg, you can do things like:
-Fu$FPC_ROOT$\$FPCVERSION\units\$FPCTARGET\*
(Shame that CFGDIR does not get 'translated' or there is a common ROOT that can be set, as it would avoid the use of FPC_ROOT environment variable in above example and/or would allow for a more portable solution).
My editor invokes the required FPC version (user configurable tool-menu options), and that is all to it.
In order to "switch" on commandline i use an environment variable for the FPC version and a small script that listens to the name fpc. I try to avoid depending on paths as FPC does not depend on it.
An alternative to using a script might be a small front-end that adds an extra parameter for supplying the version (that get's stripped from the argument list) and then invoke the corresponding fpc with the 'usual' parameters, just passing those to FPC.
Things can get a bit more complicated using multiple installations targeting different processors belonging to the same line (m68k, arm).